1. Field of the Invention
The present invention relates to fluid mixing devices and fluid—solid separating devices. More particularly, the present invention relates to fluid mixing devices and fluid—solid separating devices which include a static material mixing apparatus and a cap. The present invention also relates to methods of using same.
2. Description of the Related Art
Static mixers are known in the art as devices that provide a way to mix materials without a motor (or rotor) and the energy required to power the motor (typically by spinning) and/or provide a swirling and/or agitating action to cause the materials to mix without requiring an energy source for the mixing action to occur.
One such type of static mixer includes a number of vanes arranged sequentially within a conduit. Whereas it is normally desirable for a fluid to have a laminar (smooth) flow, the vanes are arranged to create a turbulent flow by having the material strike the vanes on its path through a conduit (e.g., a pipe or barrel) by dividing the flow into a series of sub-streams, and then causing the sub-streams to recombine with a swirling action when exiting a particular vane, only to strike a successive vane and subdivide again, followed by recombination. The action of the material dividing and recombining as it passes through the conduit results in a completely homogeneous mixture being discharged from the conduit.
In the aforementioned mixer, the vanes are often constructed of complicated geometric configurations that are not only expensive to manufacture, but have been known at times to cause large variations in the pressure of the materials as they are being mixed by their passage through the conduit. The large drops of pressure at some portions of the configuration of the vanes are particularly undesirable, as the difference in the pressure at different points may cause the acceleration of the fluid in the pipe to reach undesirable levels.
U.S. Pat. No. 4,511,258 to Federighi et al. (herein after “Federighi '258”) incorporated herein by reference discloses a mixing element that is simpler to manufacture than the vanes and in many ways, more effective because there are no large drops in pressure. Federighi '258 discloses a symmetrically formed mixing element to eliminate precision alignment with the conduit that was often necessary when using vanes. The mixing element includes two substantially identical segments having a sinuous cross-section between opposite ends.
In U.S. Pat. No. 4,936,689 to Federighi (hereinafter “Federighi '689”) incorporated herein by reference, the inventor admits that certain prior art static mixers, which included those described in a previous patent (Federighi '258), had a shortcoming that becomes evident when mixing liquids that contain solids; such mixers are prone to clogging. In order to keep the mixer from staying unclogged, repeated maintenance at constant intervals is required, but there also needs to be a monitoring system in place to make sure there is no clogging. Not only is the use of the prior art system inefficient and costly, but the unclogging can be unpleasant when the mixer is used to mix sanitation items, such as sewage.
In addition, Federighi '689 discloses at column 3, lines 34-40 that a primary benefit of the invention is that solids suspended within the fluids can pass through an internal chamber 16 of the conduit 12 via a gap 21 between the radially spaced segments 14a, 14b. 
However, there are still clogging problems and varying drops in pressure within the conduit that are associated with prior art static mixers. Thus, there is a need in the art for an improved static mixer.
There is also a need for improved gas-liquid contacting and liquid-liquid contacting to enhance water treatment, e.g., water chlorination or water treatment with ozone, because the simple use of an in-line mixer is insufficient for efficient contacting in a small space.
There is also a need for improved compact sand filters.